Apparatus for maintaining constant weight on a well tool



oct. s, 1.957

L.. W. LEDGERWOOD, JR., ETAL APPARATUS Foa MATNTAINTNG CONSTANT WEIGHToN A WELL Toor.

Filed Jan. 29.1952

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APPARATUS FOR MAINTAININGCONSTANT WEI'GHT 0N A WELL TOOL 3 Sheets-Sheet2 Filed Jan. 29, 1952 ..-.-I ..--ll.-. -1-. Y a A ,f A 5 TIC-Sfil- QIF'@nA/cahors 0d 8, v1957 L. w. LEDGERwooD, JR.. ElM 2,809,013

APPARATUS FOR MAINTINING CONSTANT WEIGHT ON A WELL TOOL United StatesPatent() APPARATUS FOR MAINTAINING CONSTANT WEIGHT ON A WELL TOOL LeroyW. Ledgerwood, Jr. and Fredric H. Deily, Tulsa,

Okla., assignors to Esso Research and Engineering Company, a corporationof Delaware Application January 29, 1952, Serial No. 268,885 1 Claim.(Cl. 2505-24) This invention concerns a novel apparatus primarily to beemployed in a string of drill'pipej in order toV insure maintenance of aconstant weight on a tool suspended by the drill pipe. The apparatuscomprises a sliding sleeve assembly to be positioned at some point in adrill string above a tool on which it is desired to maintain a constantforce. The sleeve of this invention serves to weight the tool referredto dependent on the weight of` apparatus below the sleeve element butindependently of the weight or amount of drill string which may beemployed above the sliding sleeve arrangement. It is a particularfeature of this apparatus that means are provided for giving positivehydraulic information at the surface `of the earth as to the criticalpositioning of the sleeve element so as to avoid changes of weight onthe drill tool which isemployed.

In drilling bore holes in the earth inA the search for and production ofpetroleum from the earth, a wide variety of tools may be suspended froma tubular string of piping ordinarily called a drill string. Thus thedrill string may be employe-d to support and turn drilling apparatus,reaming apparatus, coring apparatus, logging apparatus, well cementingtools, and other types of drilling apparatus. in many cases .it becomesdesirable to force the apparatus against the bottom of thebore hole witha constant force and in some cases to provide little force on the toolat the bottom of the bore hole. It is the purpose of this invention toprovide apparatus which will permit maintaining a constant force on atool suspended from a drill string independent of the length of thedrill string and the weight of the drill'string. The invention isparticularly desirable in providing means to maintain a minimum downwardVforce onthe tool employed.

The present invention is of particular application to a type of drillingwhich has been called pellet impact drilling. Employing this `drillingtechnique, a jet nozzle is employed to direct and propel a stream ofhigh velocity pellets against the bottom of a bore hole to securedrilling action; ln the simplest form of pellet impact drillingapparatus, it becomes desirable to space the jet nozzle assembly at'afixed distance froml the bottom of the. bore hole without permittingdirect contact of any portion of the pellet impact drilling tool. Inanother form of drill bit 'used in pellet impact drilling, a mechanicalVstandoi arrangement may `be used to maintain the nozzles associatedtherewith at a fixed distance from the bottom of the bore hole. Someweight may be tolerated and preferably is employed to maintain thestandolf arrangement in Contact with the bottom of the bore hole at alltimes. However, it is desirable that the weight applied to a tool ofthis character be small and substantially constant. The presentinvention provides a means for maintaining a pellet-impact drillingapparatus in close proximity but free of actual contact with the bottomof a bore hole. ,Again, the present invention provides a means,ifdesired, for forcing the drilling tool employedagainst. the bottom of abore hole with a constant force. For 4purposes of `claritythe invention2,809,013 Patented Oct. 8, 1957 ICC will be described with particularreference to the use of pellet impact drilling tools. However, it is tobe understood that the invention is broadly applicable to criticallymaintaining desired weight on any type of tool employed in conjunctionwith a drill string in a bore hole. In this connection, for example, inone embodiment of this invention it is practical to use the apparatusfor the purpose of maintaining a large but constant Weight on aconventional rotary drilling tool. This is particularly valuable in thedrilling of deep bore holes since it becomes necessary to relieve aportion of the weight of the drill string lfrom the tool at bottom toprevent buckling and failure of the drill string.

Three different and preferred modifications of this invention areillustrated in the accompanying drawings. ln these drawings Figures 1, 4and 5 illustrate the three embodiments of the invention incross-sectional, elevational detail.

Figure 2 is a cross-sectional View of Figure l along the line II-IIwhile Figure 3 is a cross sectional view of Figure l along the lineIIIIII.

Figure 6 is a cross-sectional View of the apparatus of Figure 5 alongthe line VI-VI, the sectional elevation constituting Figure 5 beingtaken on the line V-V of Figure 6.

Finally, Figure 7 shows a cross-sectional, elevation view of a desirableadjunct to each of these embodiments if desired to minimize the weightapplied to the drilling tool.

Referring first to Figure l, an embodiment of the invention isillustrated as applied to the critical positioning of a pellet impactdrilling tool from the bottom of a bore hole. The apparatus isillustrated in operative drilling position within a bore hole 1. Thenumeral 2 designates a type of pellet impact drilling tool. A primarynozzle 3 is employed which is in uid communica tion with a drill .string5. Immediately below and concentric with the primary nozzle 3 is aventuri element 4. Fluid pumped through the drill string is ejected fromthe primary nozzle as a high velocity directed jet of fluid which ilowsdownwardly through the venturi element 4. As will be described, hard,dense, spherical pellets are entrained in the jet of fluid between theprimary nozzle 3 and the Venturi element 44 and directed downwardlytowards the secondary nozzles 6. As illustrated, a plurality ofsecondary nozzles may be employed which, if desired, may have thegeneral arrangement shown in Figure 3. The enlarged chamber 7 in thedrill head 2 between Venturi element 4 and the secondary nozzles 6performs a particular function. The diverging contiguration of thischamber transforms the kinetic energy of the jet of fluid passingthrough venturi element 4, into internal energy. Mixing of the pelletsand fluid takes place in chamber 7, and then the fluid-pellet mixture isre-accelerated through nozzles 6. Chamber 7 is preferably elongatedsufliciently to secure effective distribution of the mixed fluid andpellets to each of nozzles 6. Alternatively deflectors may be positionedin chamber 7 or the orifice size of the nozzles 6 may be adjusted toobtain the desired distribution of fluid and pellet ow. It will beobserved that the secondary nozzles 6 extend through a drilling headmember providing a substantially llat termination which is positionedabove the bottom of the bore hole. Pellets ejected through the nozzles 6to some extent rebound against the flat drilling head member. Again thefluid employed to propel these pellets exerts a jet reaction whichcombines with the action referred to so as to provide an upwardcomponent of force tending to maintain 4the drilling tool in theposition shown at a spaced distance from the bottom of the bore hole. Inaddition, the fluid moving upward after 3 contact with bottom will exertan upward force on head 2.

The general uid ow at the bottom of the 'bone hole carries the pelletsoutwardly and then forces the pellets upwardly in the restricted annularchannel provided between the wall of the bore hole and the periphery ofthe drilling member 2. Pellets carried upwardlykin this annular spacemay settle from the stream of drilling fluid above the upper lip of thedrilling head 2 which is arranged as la sleeve member 8 to form anannular channel between the nozzle support member 9 and the sleeve 8.This separation of the pellets occurs in lange part due to the `factthat fluid above sleeve element S has =a substantially reduced upwardlinear flow velocity due to the enlarged annular space available for owof uid. Again, nozzle 3 arranged as shown, creates a-n aspirating actioneffective to cause the circulation of pellets downwardly within thesleeve member 8 into the path of fluid ejected from nozzle 3.Consequently, the continued circulation of pellets, las described,occurs duri-ng passage of fluid through the nozzles referred to.

As brought out, in the operation of a tool of this character there areone or more components of force directed upwardly against the tool. Itis the purpose of this invention to provide a practical means `for usingthese upward components of force to maintain the desired positioning ofthe tool with respect to the bottom of the bore hole. Alternatively, itmay be considered that means are required to maintain a constant weightor downward force on the type of tool referred to.

ln accordance with this invention a sleeve coupling is provided betweenan upper portion of the drill string and a lower portion of the drillstring to which the tool is attached. Thus in Figure 1 drill string 5 isprovided with an internal recess acting as -a sleeve to accommodate thelower section of tubing identified by numeral 9. The upper terminationof tubing 9 is permitted to slide freely within the lower sleevetermination of tubing 5. It is necessary that the sleeve connectedtubings be maintained in fluid tight relationship. To accomplish this anannular packing member 10 may rbe positioned rat one or more points ofcontact between tubing 9 and the sleeve on tubing 5. Provision is alsorequired to limit the extent of relative movement of the interconnectedtub-ing members. Thus, in introducing or removing the tool illustratedfrom the bore hole, it is necessary that tubing 5 be enabled to hold andlift the lower tubing section 9 carrying the attached tool. For thispurpose pins 11 may be fixed in the outer sleeve member 5 extendinginwardly to lit in slots provided in the inner sleeve member 9. Thisarrangement is particularly illustrated i-n Figure 2. By virtue of thearrangement of pins referred to in suitable longitudinals slots in theinner tubular member 9, the pins impose denite limits of relativemovement between the two interconnected tubing elements. Again, thisarrangement permits transmission of rotary torque from the upper tubularelement to the lower tubular element to permit the drilling operationscontemplated.

It is a particular feature of this arrangement that ports 12 arearranged within the inner sleeve member 9. These ports are so positionedthat when tube 9 has moved so as to approach the lower limit of movementwith respect to drill string 5, the ports 12 extend below the lower edgeof the sleeve element of drill string 5. A fluid passage is thus exposedso that lluid may pass through the drill string and through the ports 12into the bore hole. Ports 12 are shaped to have suflicient open area sothat when this occurs a substantial pressure drop will occur within thedrill string. This condition can readily be detected at the surface ofthe earth to inform an operator that the drilling tool lhas approachedthe limit of movement with respect to the drill string 5.

In employing the Yapparatus of Figure l the drilling tool 2 Vattached asillustrated may be Ilowered to the bottom of a bore hole. Drilling uidis pumped downwardly through the drill string to permit circulation anddrilling with the pellets referred to. The upward force provided by therebounding and circulation of the pellets and fluid against the drillinghead may be considered to lioat the lower portion of the apparatus at apredetermined offbottom position within the sleeve connection provided.However, as drilling proceeds, if 4drill string 5 is held at a fixedlevel, the lower portion of the apparatus will eventually drop untilports 12 Iare exposed. At this time the drop in hydraulic pressurewithin the drill string will establish the necessity of lowering thedrill string 5 a distance less than the limit of movement provided bythe pins described. Lowering the -drill string as required will notincrease the weight on the drilling tool and this quential type ofoperation may be continued as required. Alternatively, if desired, inemploying the apparatus described, the drill string 5 may be lowered ata constant rate, somewhat slower than the drilling rate. In this case itis only necessary to infrequently increase the lowering rate wheneverports 12 become exposed so as to cause a drop in the back pressure ofthe drill string.

Referring now to Figure 4, an embodiment of the invention is illustratedemploying the same principles of operation but providing hydraulicinformation when the interconnected sleeve elements approach eitherlimit of relative movement. Referring to Figure 4, an inner tubularmember 15 is employed which may consist of or may be connected to adrill string extending to the surface of the earth on which the entireapparatus may be suspended. As illustrated, a sleeve element 16 may bemaintained in close sliding relationship with the inner tubular element15. The sleeve element 16 may Ibe attached to a drilling tool to beemployed in the bore hole or may be attached to any desired length andweight of tubing suspended on the sleeve member 16 and connected at itstermination to -a ldrilling tool. A number of ports 17 may be cutthrough the wall of tubular member 15. A

firstY set of ports 18 arranged at `a particular level on sleeve 16, arealso provided which are adapted to register with ports 17 -at -a fixedposition of sliding relationship between the elements 15 and 16. Asecond set of Vports 19 Iare also cut through sleeve member 16 which, asillustrate-d, are arranged at a displaced point along sleeve 16 abovethe first set of ports 18. Again, ports 19 are adapted to register withthe inner ports 17 when the inner tubular member 15 is moved upwardly sothat the ports 17 are at the same level as the ports 19. Packingelements 20 may be positioned around the ports 17 to maintain sleeve 16in fluid tight relationship with tubular member 15.

In the apparatus of Figure 4 an outer sleeve member 22, fixed to andsuspended from the upper tubular member 15 extends downwardly to provideshoulder elements 23 on which latches 24 of sleeve 16 may bear.Consequently in introducing or lowering this apparatus into a bore hole,sleeve 16 may slide downwardly so that lzaztches 24 will bear onshoulders 23 of the outer sleeve Projections 25 are positioned on theinner surface of the sleeve 16. These projections are adapted to limitthe downward movement of tubular member 15 with respect to sleeve 16.

The operation of this apparatus is similar to that of the apparatus ofFigure 1 formerly described. Assuming that drill string .15 is held at aconstant level while a drilling .-tool lattached to sleeve 16 isprogressing downwardly in a bore hole, sleeve 16 will gradually dropdownwardly with respect to the inner tubular member 15. This will causeports 19 to register with ports 17 in time. As a result, fluid may passfrom the inside of tubular member 15 through these ports and through themultitudinous perforations Z9 provided in the outer supporting sleevemember 22. An operator at the surface of the earth will, therefore,appreciate the necessity for lowering drill Os tri'ng 15. Drill string15 may then be lowered until ports 17 register with ports 18. At thistime the pressure in the drill stem will again drop informing anoperator that the lower limit of movement has been reached. Y

In order for this apparatus to operate in the most desirable manner,certain modifications are desirably included in the apparatus. It isimportant that the inner tubular member'1`5 extend downwardly for asubstantial distance belowthe ports 18 in sleeve member 16. An annularseal member 31, which may be xed to the lower termination of tubularmember 15, is employed to maintain a fluid tight seal between thismember and sleeve 16. It is necessary that this packing seal 31 bepositioned below ports 17, a distance greater than the distance betweenports 18 and 19 which` are positioned in the sleeve member 16. Y

Effective sliding relation of tubular member l5 and sleeve 16 may bemaintained by providing annular collars on tube which may be machined toclose limits of tolerance within sleeve 16.

. As described, it is not necessary to retain the rotational registerbetween the sleeve elements of this apparatus. This becomes practical byusinga sufficient number and angular arrangement of the ports intendedto register so that at least one pair of ports will register regardlessof the rotational relationship of tube 15 with sleeve 16. However, ifthis apparatus is to be employed with'a tool to be rotated in a borehole, it is necessary to provide a slotted key-way or the equivalentbetween tube 15 and sleeve 16 for the transmission of torque.

Referring now to Figure 5 and Figure 6, a modiiied form of the apparatusof Figure 4 is illustrated. ln the apparatus of Figure 5 the drillstring or tubular member attached thereto is designated by number 35. Anouter sleeve member 36 is maintained in itted sliding relationship withtube 35. Sleeve 36 extends downwardly for attachment to a tool to beemployed in the bore hole. Ports 37 are provided which pass through thewall of tube 35. Packing seals 38 are employed around these ports so asto maintain a fluid seal between these ports and the clearancepassageway between sleeve 36 and tube 35. A first set of ports 39 areprovided at one level in sleeve 36 and a second set of ports 40 aremaintained at a different level in sleeve 36. As illustrated, in Figure6, in this embodiment of the invention, longitudinal keyways are cut intube 35 and sleeve 36 to accommodate the keys 48. These keys areemployed to maintain a tixed rotational register between members 36 and35 and to permit transmission of rotary torque from member 35 to sleeve36. Again the keys 48 serve to maintain ports 37 of tube 35 in the samevertical plane as ports 39 and 40 of sleeve 36.

Latch recess 45 may be cut in an upper portion of sleeve 36. This latchrecess is adapted to engage latching dogs 46 which are pivotallyattached to tubular member 35. Latching dogs 46 are at all times urgedoutwardly by means of suitable springs. Consequently, as illustrated inthe drawing, if sleeve member 36 is lowered with respect to tubularmember 35, the latching dogs 46 will be forced into the recess 45. Bythis means tube 35 can be used to lift the entire apparatus from thebore hole. It will be observed from Figure 6 that latching dogs 46 andrecess 45 are positioned on members 35 and 36 out of vertical alignmentwith the ports 37, 39, and 4l). Again, in the apparatus of Figure 5, alower packing seal 38 is employed to maintain the fluid seal between theinner tubular member 35 and sleeve 36. It is necessary that this packingseal 38 be positioned below the latching dogs 46 at a distance greaterthan the distance between ports 39 and ports 40.

In the apparatus of both Figure 4 and Figure 5 it is possible to securepositive hydraulic information as to which of the sets of ports areexposed on movement of the innertubular member... Thus,.referring toFigure 5, for example, `the upperports 40 may be cut to have asubstantially greater area than the lower ports 39. Consequently, whenports 37 register with ports 40, a substantially greaterdecrease frominitial or operating pressure will occur than when ports 37 registerwith the ports 39. This provision enables an operator at the surface ofthe earth to immediately tell the relative position of tube with respectto sleeve 36.

Itshould be observed that in each of the embodiments described, thetubular and sleeve elements of the apparatus may be reversed.

It may be noted that the apparatus as described is particularly adaptedfor automatic lowering of a drill string while maintaining constantweight on a tool suspended in a bore hole. Thus the hydraulicindications provided by the sleeve arrangements described may beemployed to operate theAhydraulic brake associated with a loweringwinch. Release of hydraulic pressure caused on the sleeve arrangementreaching a limiting position may thus automatically release the brake onthe winch to secure a desired lo'weringof the drill string. Anarrangement of this nature is disclosed in co-pending application Ser.No. 268,883, of Leroy W. Ledgerwood, Jr., tiled January 29, 1952, nowPatent No. 2,724,574.

In the use of this invention to maintain a tool displaced from thebottom of a bore hole, or in light contact therewith, it is desirable tosupplement upward forces acting on` the sleeve arrangements described.For example, in positioning a jet nozzle at some distance from thebottom of a bore hole, the upward jet reaction against bottom may beaided by-a hydraulic arrangement acting on the sleeve arrangement. Asuitable hydraulic arrangement for this purpose is illustrated in Figure7.

In this drawing, the numeral 5i identities the drill string extendingfrom the surface of the earth. Sleeve element 53 maintained in slidingrelationy with drill string 5l is connected to a lower tubular member 52which may be connected in turn to any desired drilling tool. A -cylinder54 is fixed to and extends around drill string 5l, depending downwardlyto enclose the upper portion of sleeve 53. The upper lip of sleeve 53may be enlarged to form a piston 57 slidable within cylinder 54. Apacking seal 55 is maintained at the lower termination of cylinder 54 toprovide a uid seal between the cylinder and sleeve 53. A -conduitpassage 56 may extend through the wall of the cylinder terminating in anorifice on the inside of cylinder 54, near the bottom thereof. Thisprovides a uid passage between the interior of drill string 51 and theinterior 0f the cylinder beneath piston 57.

In operation the apparatus functions as follows: drilling mud will bepumped down drill string 52 to supply a tool such as shown in Figure l,for example. The pressure within drill string 51 will consequently lbehigher than the pressure exterior of the drill string. As a result,drilling Huid will pass through conduit 56 into cylinder 54, providingan upward force against piston 57. A port 58 in the upper portion of thelcylinder permits this force to move the piston upwardly if this forceexceeds downward force components on sleeve 53. In this way, the pistonacts to provide a constant upward -force on the lower sleeve elementsindependently of any upward forces contributed by the tool used. Theupward force contributed by the piston arrangement may critically be setby xing the area of the piston and the pressure differential maintainedacross the piston. A lower port 59 is provided in sleeve element 53 toprovide hydraulic information of the approach to the limiting positionof movement of the sleeve arrangement.

It is to be understood, as already stated, that the principal purposelof the structure shown in Figure 7 is to supplement the upward forcesthat tend to maintain the jet nozzle at some distance from the bottom ofthe bore hole. When the pressure of the fluid in the drill pipe exceedsthe pressure of the fluid in the well, which is the situation l thatwould obtain during drilling, an upward pressure will be exerted againstpiston 57. If the pressure differential i`s suficiently great torovercome the downward forces contributed by the Weight of membersSlaandl 53 and any elements depending therefrom, and by the downwardpressure exerted on piston 57 'by the fluid in the bore hole, andcounterbalanced by anyv upward reaction 4from the jet nozzle at thebottom of the bore hole, piston 57 would travel to the top of thecylinder. The apparatus would not be designed to bring about thisresult, however, since the structure of Figure 7 is intended merely tosupplement the upward forces exerted on the drill nozzle. Hence thecylinder and piston arrangement should be of selected size, for theoperating pressures being used and for the weight of the elementsdepending from. the piston, such that the upward force againstpiston S7would not be great enough to cause piston 57 to move to the top of thecylinder by this hydraulic force alone. If this hydraulic force, plustherupward force exerted against the drill nozzle is sufiiciently great,piston 57 will tend to move upwardly. It should be entirely obvious,however, that as soon as piston 57 begins to move upwardly to any extentthe jet nozzle on the drill will be lifted a greater distance from thebottom of the bore hole, which will in turn reduce the lifting effect ofthe jet reaction at the bottom of the bore hole. Hence piston 57 willmove upwardly only to the extent necessary to bring the upward anddownward forces into balance.

What is claimed is:

A coupling arrangement for a drill string and a well tool which isconnected to and depending from the drill string comprising a pair oftubular members maintained inv fluid-tight telescopic slidingrelationship, one of said members being iixed to the drill string, andthe other of said members being fixed to the tool,means limiting theretracted and extended positional relations of the tubular members, atleast one first port in a first of said tubular members, at least onelsecond port in the second of said tubular members, said first andsecondports being so positioned as to register with each other when thetubular members reach a position adjacent their outermost extension fromeach other, at least one third port in said first tubular member spacedlongitudinally from said first port, said third and said second portsbeing so positioned as to regi-ster with each other when said tubularmembers are retracted relative to each other, the total aggregatecross-sectional area of said third ports differing substantially fromthe total aggregate cross-sectional area of said first ports.

References Cited in the file of this patent UNITED STATES PATENTS1,660,033 Braswell Feb. 21, 1928 1,891,328 Le Comptel et al; Dec'. 20,1932 2,317,021 Bassinger Apr. 20, 1943 2,341,832 Verheul et al. Feb. 15,1944 2,549,198 Hayward Apr. 17, 1951 2,586,015 Edwards Feb. 19, 1952FOREIGN PATENTS 545,271 Great Britain Y May 18, 1942

